In the wake of January’s norovirus outbreaks aboard two cruise ships — Royal Caribbean’s Explorer of the Seas outbreak infecting a record-breaking 600 passengers, and the smaller outbreak aboard Princess Cruises’ Caribbean Princess — questions like “How does that happen?” and “What are the chances it will happen to me?” fill the heads of vacationers. We consulted three experts to answer those questions, and others, about noroviruses on cruise ships:
What are noroviruses?
Noroviruses are infections that cause gastroenteritis, resulting in vomiting and diarrhea. The virus thrives in the winter, and outbreaks commonly spread throughout groups of people who are in enclosed spaces for prolonged periods of time, such as nursing homes, schools, and (of course) cruise ships.
“A norovirus is often mistaken for the flu, but the difference between the two is that the flu is a respiratory virus whereas norovirus infects your digestive tract,” points out researcher Kristen Gibson, Ph.D. According to the Centers for Disease Control and Prevention (CDC), the norovirus results in 70,000 hospitalizations and 800 deaths per year in the U.S., but almost all of those deaths are among elderly people.
What are the symptoms?
Symptoms include nausea, headache, abdominal cramps, diarrhea, and vomiting. For otherwise healthy people, the symptoms last 24 to 48 hours.
“Only about half the affected patients develop low-grade fever. The symptoms of a norovirus come on without warning, which is why it spreads so effectively. If someone is in a public area and gets sick unexpectedly, the germs can spread through the air or settle on surfaces, exposing the people around them to the virus,” explains infectious disease specialist William Schaffner, M.D.
How are these diseases spread?
Noroviruses are very easily transmitted, passing from human to human after vomiting or having diarrhea and not washing your hands well enough, or if someone comes in contact with an infected area that hasn’t been thoroughly cleaned. But that’s not all: Noroviruses can also spread through the air. “After someone vomits, the virus can settle on someone’s hands, mouth, or even nearby surfaces,” says Ben Lopman, Ph.D., epidemiologist with the CDC.
“You can carry the virus without feeling the symptoms; many viruses get aboard cruise ships when someone is carrying the virus in their intestinal tract but hasn’t felt the symptoms yet,” explains Schaffner. He adds that you can still spread the virus even after you’re feeling better, so it also gets aboard cruises when people who were sick a week ago are feeling better but are still contagious.
How can you avoid becoming infected?
All experts agree that the best way to protect yourself is through good hand hygiene — wash thoroughly before touching food and after using the bathroom. “The soap does not have to be antibacterial as this is ineffective against viruses,” Gibson points out, adding that studies have shown that hand sanitizers do not effectively kill noroviruses. Since the virus spreads most rapidly among people in enclosed environments, Schaffner advises avoiding foods that aren’t cooked — like sandwiches and salads — during an outbreak because the person who prepared the food might be carrying the virus.
It’s also important to note that if a cruiser gets sick, the crew will quarantine that passenger in his or her cabin to treat the illness and avoid spreading the virus.
How can you treat the virus?
There is no drug that kills the virus. Doctors encourage patients to stay well-hydrated. “Medical treatment is normally not required except in the case of severe dehydration, which is usually among elderly or otherwise unhealthy people,” says Gibson.
Why have these outbreaks on cruises been in the news?
Lopman says that the vast majority of outbreaks reported to the CDC occur in healthcare facilities, such as nursing homes. Schools and restaurants are also common settings; cruise ships only report a handful every year.
According to the CDC, cruise ship outbreaks are big news because health officials are required to track illnesses on ships — but not at hotels and resorts. Therefore, outbreaks are found and reported more quickly at sea than on land. Also, since outbreaks in schools, hospitals, and on cruise ships are so large, they result in big news stories.